Sealant compositions comprising polyacetal compound, filler and drier



United States atent Ofilice 3,53,792 SEALANT COMPUSHTIBNS COMPRISING PDLY- ACETAL COMPOUND, FILLER AND DRER Carol K. lkeda, Wallingford, Pa, assignor to E. I. du Pout de Nernours and Company, Wilmington, Del, :1 corporation of Delaware No Drawing. Filed Aug. 5, 1958, Ser. No. 753,199

8 Claims. (Cl. 260-411) This invention relates to sealants and more particularly to air-drying sealing compositions having an air-drying non-volatile organic binder comprising a compound char acterized by a plurality of 2-vinyl-l,3-cyclic acetal radicals and having dispersed in the binder a particulate inert filler material which is insoluble therein, the sealant being fuither characterized by a high consistency value and as being easily-workable and pressure-deformable with such pressure-applying devices as a calking gun, putty knife, doctor knife or roller.

Sealing compositions are variously designated in the trade according to the particular utility of the composition, such as for example, calking compounds, glazing putties, seam sealants, metal repair putties, wood putties or plastic wood, crack fillers and the like.

Five general classes of sealants and their respective significant characteristics are described in Adhesives and Sealants in Building, Publication 577, April 1958, Building Research Institute National Academy of Science, National Research Council, Library of Congress Catalog Number 58-60022 pages 14 to 18. The general class of calking compounds is further described on pages 41 to 45 Although some non-volatile film-forming materials per se can be used as sealants, sealing compositions usually comprise the organic film-forming material, designated as the binder, modified by pigmentation with inert finelycomminuted particulate materials which are designated as fillers. Inorganic filler pigments or extender pigments, color pigments and particulate organic materials which are insoluble in the fluid organic binder, such as comminuted cellulosic materials and fiber floc, are typical filler materials.

Pigmentation or filling of the binder with filler materials is primarily for the purpose of providing the sealant with desired physical characteristics, particularly in reference to consistency.

Sealants can be formulated on a solvent-free basis. However, volatile solvents or diluents ordinarily are included in some compositions to desirably adjust the consistency downward. The presence of volatile components in the sealant composition usually causes shrinkage of the applied product and to avoid excessive shrinkage, the volatile solvents are used only in relatively small proportions sufiicient to promote the desired consistency adjustment.

The various types of sealants are also classified according to consistency, such as calking gun grade ranging from light to heavy consistency suitable for extrusion through the orifice of an ordinary calking gun, and various knife grades which ordinarily are too heavy in consistency for extrusion through the orifice of a calking gun and are applied by putty knife or similar pressure-applying device.

The consistency of sealants extends far beyond the ordinary range of viscosity instruments designed for measuring the consistency of fluids, such as paints, oils, etc. For the purpose of measuring the heavy consistency of sealants, the Krebs-Stormer viscosimeter used to measure the consistency of exterior house paints and enamels according to the procedure of A.S.T.M. Designation D-56255 has been modified by replacing the Krebs paddle-type viscosity spindle with a special 2-arm consistency spindle and applying heavier than ordinary loads to motivate the spindle. Consistency values reported herein for the sealants are determined with the special consistency spindle by measuring the time in seconds required for 50 revolutions of the spindle under an applied load of 2000 grams.

The special consistency spindle consists of a spindle shaft of inch round rod 5 inches long having two radial arms projecting at from the vertical spindle rod. These arms are of inch round rod, each having a radial length of inch. The center line of one arm is inch from the bottom end of the spindle rod and the center line of the other arm is 7 inch from the bottom end of the spindle rod. The radial displacement of one arm in reference to the other is 180.

In carrying out the consistency measurement, the sample of sealant is placed in an ordinary round A pint tin can which is securely clamped in the viscosimeter with the Z-arm spindle immersed in the sealant to a depth of 1% inches. The load of 2000 grams is applied and the spindle is allowed to rotate l0 revolutions before starting the measurement. Then the number of seconds per 50 revolutions of the spindle is determined as the consistency measure.

Using the above described measuring means, ranges of consistency of typical sealants are as follows:

Classification: Consistency in seconds Light gun grade 5 to 35 Gun grade 35 to 50 Heavy gun grade 50 to Light knife grade 100 to 250 Knife grade 250 to 1000 Heavy knife grade 1000 to 5000 Some sealants having a consistency even higher than 5000 seconds can be satisfactorily applied. For convenience in the specification, the term putty-like consistency is used to define consistency values ranging from 5 to 5000 seeonds using the indicated procedure.

In comparison, ordinary linseed oilAbased white exterior house paints at satisfactory brushing consistency are characterized by a viscosity of from about 70 to about 100 Krebs units determined by the method A.S.T.M. Designation D-562-55. A representative. house paint having a viscosity of 88 Krebs units exhibited a consistency of 8 seconds when a load of 50 grams was substituted for the 2000 grams in the above-described method designed for measuring the consistency of sealants. In addition to the high differential in consistency, the sealants are distinguished from ordinary paints by significantly higher yield values and plastic viscosity factors.

Properties of sealant pertinent to their utility arcadhesion to a substrate, durability or retention of physical characteristics on aging, and shrinkage-resistance. For most uses, it is desirable that the dried or cured sealant be a durable impervious compact mass which is waterresistant, weather resistant and adheres satisfactorily to the various types of substrates with which it may be in contact. For many uses, shrinkage of the sealant up to 20% can be tolerated, but particularly for glazing purposes and the like, shrinkage values approaching zero, preferably less than 3%, are desirable. In application, the sealant is desirably an easily-workable, pressure-de' formable, high consistency mass which is adequately high in yield value to resist slumping or sagging, and which rapidly dries to remain in place and resists extraction of the binder by porous substrates.

Although linseed oil putties are characterized by many of these desirable properties, they are slow curing and before the cure is complete, porous substrates, such as wood, can extract the oil binder from the dispersed filler.

This extraction usually leaves the residual putty as a weak, oil-deficient mass which is inadequately weather resistant and poor in durability. Sealing compounds formulated with organic polymeric binders ordinarily require a significant proportion of volatile solvent to dissolve or disperse the binder. Such products either dry by volatile loss of the solvent or by a combination of solvent loss and catalyzed cure of the polymeric binder. Some sealants merely surface dry with the dry surface skin enveloping uncured or incompletely cured material.

The principal object of this invention is to provide sealant compositions characterized by advantageous improvements over ordinary calking compounds, putties and sealants in reference to the aforementioned deficiencies. More specifically, the primary object of this invention is to provide an easily-workable and pressure-deformable sealant composition which is rapidly-curable on exposure to an oxygen-containing atmosphere to a weather-resistant, durable mass which is adherent to the substrate to which it is applied and which resists significant extraction of the binder by absorbent substrates. Another object is to provide a sealant having a composition formulated substantially free of volatile components whereby on drying or curing, the dried product is characterized by little or no shrinkage. A further object is to provide a method of calking, sealing or repairing an article with a novel shrink-resistant, air-curable sealant which rapidly cures to a durable, air-tight, water-resistant and weather-resistant seal or space-filling calk.

These and other important objects which will be apparent as the description of the invention proceeds are accomplished by dispersing a filler composition comprising at least one particulate inert filler material in a nonvolatile fluid organic binder comprising at least one vinyl cyclic acetal compound having a plurality of radicals of the following general chemical structure represents a plurality of carbon atoms in the acetal ring, a" :being an integer having a value of at least 2. All but one of the indicated unsatisfied 2a valences of these carbon atoms of the acetal ring are satisfied by monovalent radicals of the class consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, chloroalkyl, fiuoroalkyl, alkoxyalkyl, cyano, chloroalkoxyalkyl, fluoroalkoxyalkyl, cyanoalkoxyalkyl, cyanoalkyl, alkenyl, chloroaryl and fluoroaryl when a" is 2, and consisting additionally of fluoro, chloro, acylamido and phenylsulfonyl when where is the valence through which the vinyl cyclic acetal radical is linked to the remainder of the compound. A catalyst comprising a siccative metal drier in an effective proportion sufficient to catalyze air-curing of the binder is included with the binder composition to accelerate drying. The composition can range from a preponderance of binder to a preponderance of filler, the non-volatile organic binder being present in an amount sufiicient to uniformly wet the filler composition to a pressure-deformable cohesive mass and the filler being present in an amount sufficient to provide the sealant with the desired consistency. In utilizing the sealing compound, it is applied to a substrate by pressure-applicator means, such as a putty knife, doctor-blade, calking gun, extruder, or pressure roll and allowed to dry or cure in an oxygencontaining atmosphere.

The new chemical compounds per se having a plurality of the above identified vinyl cyclic acetal radical which are useful in practicing this invention are more fully disclosed and claimed in my copending United States Patent applications Serial No. 683,021, filed September 10, 1957, Serial No. 730,070, filed April 22, 1958, both now abandoned, Serial No. 737,506 filed May 26, 1958 now US. 3,010,923, and Serial No. 737,507 filed May 26, 1958 now US. 3,010,918.

The characteristic common to all of these new compounds is the presence of a plurality of the radicals for which the structural formula is shown above. This radical is referred to herein for the sake of brevity as the 2-vinyl-1,3-cyclic acetal radical, or simply the vinyl cyclic acetal radical, it being understood that a substituent other than hydrogen can be attached to the apha carbon atom of the vinyl radical as indicated, that the carbon atoms in the ring can vary in number as indicated and can have substituent a indicated.

Also for the sake of brevity and convenience of identity through the specification and the appended claims, these new compounds having a plurality of the defined 2-vinyl-l,3-cyclic acetal radical are referred to as polyacetal compounds. Compounds having only one such defined 2-vinyl-1,3-cyclic acetal radical per molecule are referred to an mono-acetal compounds.

For reasons of economy, ease of operation and availability of suitable starting materials, the preferred number of 2-vinyl-1,3-cyclic acetal radicals in a given compound is 2 to 4, although higher number species can be made. For example six of such radicals can be attached to a hexavalent radical derived from mellitic acid. Obviously mixtures of compounds can yield compositions in which the overall average number of vinyl cyclic acetal radicals per molecule is not a whole number.

From the standpoint of rapid air-drying or insolubilization in the presence of oxygen, the preferred new compounds are those in which the vinyl cyclic acetal equivalent does not exceed about 500; in other words, the weight of compound required to provide one gram equivalent of cyclic acetal radical does not exceed about 500 grams.

The polyvalent connecting radical which joins a plurality of the vinyl cyclic acetal radicals is not critical. However it will be obvious to persons skilled in the polymerization art that substituents known to have an inhibiting effect on vinyl polymerization should be avoided or placed in a shielded or sterically hindered position so that the inhibiting effect is minimized. Likewise, strongly acidic radicals which tend to open the cyclic acetal ring, and radicals which form insoluble complexes with metallic driers, are preferably avoided. Such obvious precautions yield compounds which offer the maximum advantages of this invention.

Any of the vinyl cyclic acetal compounds embraced by my copending applications are operative in practicing this invention. Esters and ethers having a plurality of 2vinyl-l,3-cyclic acetal radicals derived from the 2- vinyl-1,3-cyclic acetal-alkanols represent preferred classes of compounds because of ease of preparation and availability of the starting materials.

Specific examples of useful esters having a plurality of the vinyl cyclic acetal radical are:

(1) Diesters of 2-vinyl-1,3-dioxolane-4-butanol, 2-

vinyl-1,3-dioxolane-4-methanol, Z-Vinyl-S-methyl-S-methylol1,3-dioxane respectively and dicarboxylic acids such as orthophthalic, isophthalic, terephthalic, di-, tetraand hexahydro derivatives of these benzenedicarboxylic acids, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, dimerized vegetable oil acids (predominantly dimers and trimers of unsaturated C fatty acids), maleic, fumaric, acetylene, dicarboxylic, itaconic, cyclopentanedicarboxylic, cyclopropanedicarboxylic, camphoric, naphthalene dicarboxylic, hydrogenated naphthalene dicarboxylic acids, dicyclopentadiene dicarboxylic, 3,6- endomethylenetetrahydrophthalic, chlorendic acid, diglycolic, thiodipropionic, cyclohexenedicarboxylic, acetonedicarboxylic, acetamidomalonic, azodicarboxylic, citraeomic and cyclobutanedicarboxylic.

(2) Triesters of the aforementioned alkanols and tricarboxylic acids: tricarballylic, aconitic, 1,2,3-cyclopropanetricarboxylic, citric, and hemimellitic.

(3) Tetraesters of the aforementioned alkanols and tetracarboxylic acids: pyromellitic and naphthalene-tetracarboxylic.

(4) Pentaesters of the aforementioned alkanols and benzenepentacarboxylic acid.

(5) Hexaesters of the aforementioned alkanols and Inellitic acid.

(6) Esters of maleic-modified rosin acids and maleicmodified tall oil acids and the aforementioned alkanols.

In addition to these esters having a plurality of the vinyl cyclic acetal radical linked to the compound by carboxylate linkages, esters of amphoteric compounds and other compounds which function as acids in esterification reactions in the absence of the carboxylic radical, such as for example, cyanurate esters and the ortho esters of acids of silicon, titanium, zirconium, germanium, tin, aluminum, boron, and phosphorus, are also useful in practicing this invention.

Typical examples of useful ether compounds are the diethers of polymethylene glycols, diethers of ethylene glycol, diethylene glycol and higher polyethylene glycols, diethers of polytetramethylene glycols, diethers of dihy-droxybenzenes, and diethers of bis-phenols, such as diphenylolpropane and diphenylolmethane, and an alkanol containing the 2-vinyl-1,3-cyclic acetal radical.

While the above-defined polyacetal compounds per so can be adequately used as the sole non-volatile binder of some sealant compositions, it is usually desirable to combine the poly-acetal compound with an auxiliary filmforming organic binder material to provide sealants having the pertinent consistency of at least 5 seconds.

Typical examples of polymeric auxiliary binder materials useful in combination with the poly-acetal compound are: acrylic acid ester resins, methacrylic acid ester resins, polyvinyl acetate, vinyl chloride/ vinyl acetate copolymers, epoxy-polyether resins, polyamide resins; cellulose esters such as cellulose acetate, cellulose propionate, cellulose acetate/butyrate, cellulose acetate/sorbate, cellulose ethers such as ethyl cellulose, polyester resins resulting from esteri-fication of low molecular Weight aliphatic diols, such as ethylene glycol, pentanediol, diethylene glycol, triols, such as glycerol, or mixtures of aliphatic polyols, and a dicarboxylic acid, such as phthalic, isophthalic, terephthalic, sebacic, adipic, and dimerized fatty acids comprising preponderant'ly dicarboxylic dimers of C unsaturated fatty acids such as linseed oil acids; and alkyd resins having various types of monofunctional modifiers in the polyester composition.

Another useful class of auxiliary binder materials are the glyceride tri-esters of C to C unsaturated fatty acids which can be in the natural raw state, refined, blown, bodied, isomerized or dehydrated.

Still another useful category of auxiliary binder materials is represented by polymerizable liquid monomers which readily undergo addition polymerization. Useful species of this class usually have at least one C==CH vinylidene moiety, preferably two of these moieties per molecule. Typical species are: diesters of acrylic acid or methacrylic acid and a saturated aliphatic diol, such as ethylene glycol, diethylene glycol, triethylene glycol, butanediol, pentanediol, other polymethyleneglyeols, polytetramethylene glycol and other polyalkylene glycols; dibutyl itaconate, dimethyl itaconate, styrene, alphamethyl styrene, vinyl toluene, methylene-bis-(acrylamide), divinyl benzene, tris-(acryl)cyanurate, ethyl acrylate, butyl methacrylate, glycidyl methacrylate, triesters of aliphatic triols and acrylic acid, methacrylic acid, phenyl acrylic acid and other unsaturated monocarboxylic acids having the C=CH vinylidene moiety.

A further useful class of auxiliary binder materials are the mono-acetal compounds having a single Z-vinyl- 1,3-cyclic-acetal radical of the defined chemical structure. These mono-acetal compounds can be an ether, e.g. 2-vinyl-l,3-dioxolane-4-butyl fi-cyanoethyl ether, an ester of a monocarboxylic acid, e.g. 2-vinyl-l,3-dioxolane- 4-butyl benzoate, or a mixed ester of a polycarboxylic acid, e.g. methyl 2-vinyl-1,3-dioxolane-4-butyl phthalate. These mono-acetal compounds can be used in the binder composition to control the flexibility, resiliency and hardness of the product. The mono-acetal compound, if desired, can be incorporated in the composition as a directly prepared combination of the mono-acetal compound and the poly-acetal compound having a plurality of the vinyl cyclic acetal radical. Such combinations can be obtained by controlling the relative proportions of the reactant supplying the vinyl cyclic acetal radical to less than that which is fully equivalent to the other reactant. For example, 1 mol. dimethyl orthophthalate ester-interchanged with 1.8 mols of 2-vinyl-1,3-dioxolane- 4-butanol provides a mixture of mol percent of the poly-acetal diester and 20 mol percent of the methyl 2- vinyl-1,3-dioxolane-4-butyl phthalate, the mono-acetal derivative.

The practical minimum content of the poly-acetal compound is about 20% based on the weight of the nonvolatile organic binder composition. When the auxiliary binder is present, a content of at least 1% ordinarily is required to produce a practical contribution and usually the auxiliary binder is present in an amount of at least 10% based on the weight of the non-volatile binder. The composition of the non-volatile binder mixture can range fro-m about 20% of the poly-acetal compound and 80% of the auxiliary organic binder material to 99% of the poly-acetal compound and 1% of the auxiliary binder. Preferably, the relative proportions are from 70% to 30% of the poly-acetal component and correspondingly 30% to 70% of the auxiliary binder.

The sealant composition includes a catalyst to accelerate curing, preferably air-drying, of the organic binder. The catalyst comprises at least one siccative metal drier which is a soluble salt or soap of a siccative metal such as cobalt, manganese, lead, iron, etc. and an acid such as phthalic, naphthenic, octanoic or the fatty acids of glyceride drying oils. The catalyst is present in an effective amount sufiicient to promote air-drying of the composition and usually the content of siccative drier metal is not in excess of 3% based on the weight of the nonvolatile organic binder. At atmospheric temperatures, an effective concentration of catalyst may be as low as 0.01% of siccative metal on the indicated basis. Preferably the catalyst comprises a cobaltous organic salt, especially a cobaltous ester salt, such as cobaltous butyl phthalate. Other typical examples of useful cobaltous ester salt catalysts are the half ester salts of dicarboxylic acids such as phthalic, adipic and sebacic having one carboxyl substituent thereof esterified with a saturated C to C aliphatic monohydric alcohol. These salts are significantly more effective than the ordinary siccative metal driers used in paint formulation. An effective proportion of these preferred cobaltous salts usually is in 7 the range of 0.01% to 0.3% of cobalt metal based on the weight of the non-volatile organic binder.

Still lower proportions of catalyst are effective if heating or baking of the article carrying the sealant is permissible. For example, a catalyst concentration of 0.005% to 0.0005% of cobalt metal based on the weight of the non-volatile organic binder is effective when heating is at a temperature ranging from 150 F. to 500 F.

In addition to the siccative metal drier, the catalyst composition can further contain peroxides hydroperoxides, hydrogen peroxide, and other polymerization initiators in the usual effective proportions capable-of promoting polymerization of unsaturated compounds having one or more CH vinylidene moieties. When these vinylidene polymerization catalysts are present, the concentration usually is in the proportion of 0.1% to 5% based on the weight of the binder components having the C=CH vinylidene moiety.

The filler material can be any of the particulate inert dry solid materials of small particle-size usually found in ordinary sealants, calking compounds, glazing putties, crack-fillers, wood putties, organic metal mending compounds and the like. Useful fillers preferably are finelycomminuted natural-occurring material of mineral origin, particularly siliceous minerals.

Typical examples of useful inorganic filler material are: magnesium silicate, aluminum silicate, china clay, calcium sulfate, barium sulfate, calcium carbonate, whiting, blanc fixe, magnesium carbonate, barytes, diatomaceous earth, amorphous silica, colloidal silica, surfaceesterified silica, talc, asbestos fiber, mica, powdered slate, metal powders such as aluminum, iron, zinc, magnesium, lead, copper, bronze, silver, nickel, chromium, etc., Portland cement, calcium-aluminate cements, rock dust, slate dust, pulverized slag, coal dust, sand and powdered glass.

These inorganic filler materials can be classified into three categories namely the crystalline type representing the crushed and sieved natural-occurring materials which primarily provide the sealant with body and color, the acicular type representing the precipitated, dried and sieved chemical pigments which reinforce and restrict the flow of the sealant, and the lamellar type representing leafed metals, metal flakes and other plate-like pigments which promote adhesion and flow. The filler composition can comprise any one of these categories of fillers or a mixture of species of one or more of these categories. Ordinarily, the filler composition comprises a major proportion of the crystalline type filler. Species of this type of filler usually are characterized by a particle-size of which a preponderance of particles will pass through a 325 mesh screen, and by an oil absorption value in the range of from to about 100.

The oil absorption value for the filler material is determined by the method well known to the art for characterizing pigments, extenders and fillers.

Particulate finely-comminuted organic materials insoluble in the binder of the sealant can also be used as filler materials either in place of the aforementioned categories of inorganic filler materials or in combination therewith. Typical examples of organic filler materials are wood flour, sawdust, ground wood paper fiber, chemical paper fiber, ground straw, comminuted regenerated cellulose, and natural or synthetic fiber floc. Some of the organic fillers of natural cellulosic origin contain components which inhibit the drying of the binder of the sealant. Such fillers should either be treated to remove the inhibitive components or be used in proportions at which the content of the inhibitive component is at a tolerable level.

The organic filler materials are useful in formulating wood repair putties, plastic wood and the like, and as fibrous reinforcing fillers to supplement the inorganic fillers.

The oil absorption value of the organic filler materials usually is greater than that of the inorganic species of filler and may range up to 300. Preferred species of organic filler have an oil absorption value no greater than 150 and when species of filler of higher absorption value are used, it is preferred practice to blend such species with inorganic fillers or organic fillers of lower absorption to provide a filler mixture having an average absorption value no greater than the preferential maximum of 150.

Utility of the sealant dictates the nature of the filler material used. For example, when utility is for crackfilling of inorganic materials of construction such as plaster, concrete, stone, cinder block, asbestos board, or for window glazing and other general utility purposes, the filler ordinarily is a finely-divided natural occurring siliceous material, such as the various forms of clays, talcs, silicates and silicas identified above. When the sealant is to be used to fill cracks and imperfections in metal, the product can contain metal leaf or powder as a filler component for close simulation of the metal substrate. When the product is to be used as repair putty for wood, a filler comprising predominantly particulate material of wood, or other cominuted material of natural cellulosic origin is preferred for close simulation of the substrate being sealed or repaired. Where close simulation is not important or contrast is desired or can be tolerated, any of the inorganic fillers can be used.

lnasmtuch as these filler ,materials vary widely in density, particle-size and surface-area to be wet by the organic hinder, the relative proportions of the organic binder and the filler can be varied widely in providing the pressure-deformable, cohesive mass with the desired consistency ranging from a consistency suitable for extrusion under pressure through a small orifice of a calking gun to heavy knifing consistency. The proportion of the filler material can satisfactorily range from 5% to about 400% based on the weight of the non-volatile organic binder. The preferred proportion of filler is in the range of about to about 300% on the indicated weight basis.

The indicated filler materials represent a rather limited color selection and when it is desirable to differently color the sealant, inorganic color pigments, organic pigments, dyes, lakes, and other coloring materials which are ordinarily used in paint, enamel or lacquer formulations can be used in combination with the filler materials. Inasmuch as the siliceous fillers usually have relatively low tinting strength, only small proportions of colorant material are required to provide desirable colored modifications. The auxiliary prime colorant material ordinarily is present in minor proportion and generally is not in excess of about 25 based on the weight of the filler mixture. The natural color sealant compounds can be colored to the users preference by mixing the product with colors in oil or other similar commercially available painters tinting bases.

Clear sealants can be formulated using silica, preferably colloidal silica, as the filler. Hydrous metal oxide pigments which are substantially transparent in the dispersed state can be used alone as the filler or in combination with particulate or colloidal silica filler to provide transparent sealants. In some instances, the unpigmented binder can be formulated at an adequately high consistency to permit its use as a clear sealant.

For most purposes and particularly for utility where minimum shrinkage is pertinent, the sealants are formulated substantially free of volatile solvents or diluents and usually contain no more than about 10%, preferably no more than 5% by weight, of volatile components. For some purposes, where resistance to slumping and shrinking are not particularly pertinent, a higher proportion of solvent or diluent such as up to 25% based on the weight of the product can be tolerated. Heavy consistency sealants can be thinned with solvent to a more desirable lower consistency having application advantages. Typical useful diluents are toluol, xylol, high solvency petroleum naphthas and polar solvents such as esters, ketones and alcohols.

In preparing the invention products, the organic binder and the filler can be mixed together by any of the paste mixing techniques capable of operating at paste and putty consistency. It is convenient to prepare the low consistency paste products in an ordinary paddle mixer. The W. and P. dough type mixer, stone mill, and putty chaser are particularly suitable for preparing the intermediate and heavy consistency products. Mixing order is not significantly critical, the filler can be added gradually to the organic binder or the organic binder can be added to the filler. In compositions having the organic binder as a mixture of the poly-acetal compound and a liquid auxiliary organic binder, it is usually desirable to initially wet the filler with the auxiliary liquid binder component and then add the poly-acetal compound to the pre-wet filler composition. When the auxiliary organic binder material is a soluble solid, it is usually preferable to predissolve the solid with the poly-acetal compound. It is practical to mix the solid auxiliary organic binder component, if available in particulate form, with the particulate filler and than add the poly-acetal compound to simultaneously dissolve the auxiliary solid binder material and wet the filler.

The following examples are provided to illustrate the principles and practice of this invention, but the invention is not limited by the specific embodiments illustrated. Parts and percentages are given on a weight basis unless otherwise specified.

The VDB orthophthalate diester is the liquid orthophthalic acid diester of 4-(omega hydroxybutyl)-2-viny 1,3-dioxolane, also referred to as 2-vinyl-1,3-dioxolane- 4-butanol. The designation VDB is used throughout the specification to identify this alkanol having the vinyl cyclic acetal radical. VDB alcohol and the orthophthalate diester were prepared as follows:

Preparation of 4-(0mega HydroxybutyD-Z-vinyl- 1,3-Dixolane (VDB) A three liter, three-necked flask equipped with a thermometer, a stirrer and a continuous water separator was charged with 670 g. mols) of 1,2,6-hexanetriol, 280 g. (5 mols) of acrolein containing a trace of hydroquinone inhibitor, 375 g. of hexane, 5 g. of oxalic acid, and 5 g. of hydroquinone. The mixture was refluxed (50-67 C.) with continuous removal of water for 24 hrs. (116 ml. removed). The mixture was freed of hexane and acrolein by heating to 60 C. and gradually reducing the pressure to less than 1 mm. Hg vacuum distillation (106122 C./l3 mm. Hg) of 876 g. of residue gave 642 g. of water-White oil and 225 g. of tan resin. The oil was dissolved in 650 g. of benzene, washed once with 300 ml. of 5% sodium hydroxide, once with 320 ml. of 5% sodium chloride and once with 200 ml. of 0.5% sodium bicarbonate. The organic phase was dried over anhydrous magnesium sulfate, filtered and substantially freed .of benzene at reduced pressure. After heating 30 min. at 5060 C./l mm, 582 g. of 4-(omega hydroxybutyl)-2-vinyl-1,3-dioxolane (VDB) were obtained.

Preparation of VDB Orthoph thalate Diesrer A three liter, three-necked flask equipped with a thermometer, a stirrer, a nitrogen inlet and an 18-inch helixpacked column topped with a total reflux head was charged with 194 g. (1 mol) of dimethyl orthophthalate, 413 g. (2.4 mols) of 4-(omega hydroxybutyD-Z-vinyl- 1,3-dioxolane (VDB) and 260 g. of toluene. The system was purged with nitrogen, and about 86 g. of toluene were distilled off to dry the reaction mixture and the apparatus. After cooling to about 30 C., 3 g. of sodium methoxide was added, and the mixture was heated to reflux (about C.). Toluene-methanol binary was distilled off during the ensuing 2.5 hours. A total of ml. of distillate were collected. At this point, the charge temperature was 144 C. and the vapor temperature was 109 C. The charge was cooled to room temperature and dissolved in a mixture of 220 g. of benzene and 3 00 g. of hexane. The resulting solution was washed four times with 200 g. portions of water, and the organic phase was separated and dried over anhydrous magnesium sulfate. After filtering, the mixture was substantially freed of solvent and unreacted 4-(omega hydroxybutyl)- 2-vinyl-1,3-dioxolane (VDB) by successively heating at about 60 C., then at about C., at about 1 mm. Hg, 461 g. of liquid pale yellow phthalic acid diester of 4-(omega hydroxybutyl)-2-vinyl-1,3-dioxolane were obtained.

The catalyst solution consists of cobaltous butyl orthophthalate dissolved in acetone in an amount equivalent to 10 milligrams of cobalt metal per milli'lter of solution. This same catalyst solution is used in all the examples.

The ingredients were mixed in a W. and P. mixer until uniformly distributed.

The product, characterized by a consistency of 10 seconds, was extruded from a calking gun having a .25 inch nozzle. This extruded round ribbon of sealant dried overnight at room temperature to a hard tough product. A comparison of the displacement volume of a cylinder of this extruded ribbon before and after drying indicated no detectable volume change, i.e. the product is free from shrinkage.

A maple panel and a white pine panel were each bored with holes ranging up to 1 inch in diameter and the resulting cavities were filled level with the respective surfaces with the product of Example 1. The fillings hardened overnight and no shrinkage was detectable. The hardened fill material was sanda'b'le.

The product was knifed on a bonderized steel panel at a calking thickness of about .125 inch. This coating dried overnight to a hard tough layer which adhered strongly to the metal substrate.

A window having a wooden frame was glazed using the product of Example 1 as a glazing putty and a metal framed window was similarly glazed. The putty hardened overnight and the adhesion of the putty to the wood, metal and glass was good. The hardened putty was satisfactorily painted with ordinary white house paint in the case of the wooden frame and satisfactorily painted with an ordinary metal protection paint in the case of the metal frame. The unpainted .putty shed water and Was weather resistant and durable. (There was no deleterious extraction of binder from the tiller by the Wood of the glazing frame.

'In contrast, ordinary linseed oil glazing putty did not harden overnight, exhibited poor adhesion to the glass and to the frame. This putty could not be painted satisfactorily after an overnight dry or even after one week of drying. The wood extracted oil from the binder.

Substitution of the ester mixture of VDB-orthophthalate diester and methyl mono(VDB) orthophthalate, obtained by ester interchange between 1 mol of dimethylphthalate and 1. 8 mols of VDB alcohol, for the VDB orthophthalate diester in the Example 1 formulation provides a product of comparable performance but is characterized as being less hard in the cured state because of the plasticizing effect of the mono-acetal compound, methyl mono(VDB) orthophthalate.

1 1 EXAMPLE 2 Percent by weight Magnesium silicate (oil absorption, 20) 62.4 Methacrylic acid diester of triethylene glycol 17.9 VDB itaconate diester 17.9 Catalyst, cobaltous butyl phthalate solution 1.8

The itaconic acid diester of VDB was prepared by ester interchange between the alcohol and dimethyl itaconate under the same esterification conditions as described above for the VDB phthalate except using 1% of titanium tetraisopropoxide based on the weight of the VDB alcohol as the interchange catalyst. The product was mixed with 500 milliliters of hexane and 200 milliliters of 200 ml. of 5% aqueous solution of NaCl, and centrifuged to separate the organic and aqueous phases. The organic phase was then washed twice with 250 milliliters portions of 5% aqueous NaOH and finally washed once with distilled water. The resulting solution of the product in hexane was dried over anhydrous MgSO filtered and distilled under reduced pressure to remove the hexane. The product was a pale yellow oil which ineluded a small proportion of methyl ester in addition to preponderant proportion of the VDB itaconate diester.

The other indicated components are the same as those used in the product of Example 1.

In preparing this sealant, the filler and the methacrylic acid diester of triethyleneglycol were initially mixed together in a W. and P. mixer and then the VDB itaconate diester and the catalyst were added to the prewet filler.

The product of Example 2 was found to be essentially equivalent in physical properties and identical in performance with the product of Example 1 when comparatively evaluated. The only detectable difference is a color distinction due to the omission of the high tinting strength titanium dioxide colorant from the filler composition.

EXAMPLE 3 Percent by weight Magnesium silicate (oil absorption, 54.0 Titanium dioxide (colorant pigment) 9.0

The polymeric B-cyanoethyl ether of VDB was obtained by air-blowing the monomeric ether which was prepared by reacting 1 mol (172 grams) of the VDB alcohol with 1 mol (53 grams) of acrylonitrile in the presence of 1 gram of 35% solution of trimethylbenzylammonium "hydroxide (Triton B) in methanol as the catalyst. In preparing this ether product having a single 2-vinyl l,3-cyclic acetal radical per molecule, the VDB alcohol and the catalyst were mixed and the acrylonitrile was gradually added thereto over a one hour period with agitation. The mixture was stirred for an additional hour and then neutralized with acetic acid. The reaction mixture was distilled under reduced pressure using a short Vigreux column, collecting the fraction boiling from 113 C. to 124 C. at .2 to .4 mm. of Hg. The weight of this fraction was 178 grams having a refractive index of 1.4606 at C. The viscosity was A-3 or about 0.14 poise. Nitrogen analysis indicated this product to be the beta-cyanoethyl ether of the VDB alcohol.

This monomeric ether was converted to polymeric form by adding cobaltous butyl phthalate in an amount equivalent to 0.05% of cobalt based on the weight of the monomeric monoether and blowing air through the liquid at a moderate rate for about 60 hours. The resulting low 12 molecular weight liquid polymer was characterized by a refractive index of 1.4927 at 25 C.

The sealant product of Example 3 was prepared as described in Example 2 by initially wetting the binder with the two auxiliary binder components and then combining the VDB-orthophthalate diester with the prewet filler.

The performance of this sealant of gun-grade con sistency is at least equal to that of the products of Examples 1 and 2. This product dries to a tough, slightly pliant, moderately hard calk which is not as hard as the dried products of Examples 1 and 2.

EXAMPLE 4 Percent by weight Magnesium silicate (oil absorption, 20) 53.5 Titanium dioxide (colorant pigment) 8.9 Polymeric fl-cyanoethyl ether of VDB 17.9 VDB orthophthalate diester"... 17.9 Catalyst, cobaltous butyl phthalate solution 1.8

The polymeric B-cyanoethyl ether of VDB was the same as that used in the product of Example 3.

The performance of this sealant is comparable with that of the products of Examples 1, 2 and 3. Extruded and knife coated specimens of this product dried tackfree overnight, but even on longer exposure to the air, these specimens remained soft, pliant and flexible. This product was particularly useful for calking sheet metal seams where the metal is subjected to significant expansion and contraction and vibration. For this type of utility, it is usually advantageous to include fibrous fillers, such as short asbestos fibers, in the filler composition with the siliceous mineral filler.

EXAMPLE 5 Percent by weight Magnesium silicate (oil absorption, 20) 65.5 Titanium dioxide (colorant pigment) 6.5 Polyethylacrylate 2.6 VDB orthophthalate diester 24.0 Catalyst, cobaltous butyl phthalate solution 1.4

The polyethylacrplate and the catalyst were dissolved in the VDB orthophthalate diester and the resulting binder was mixed with the filler material. Acrylate resins and methacrylate resins are commercially available in solution form in such solvents as Cellosolve acetate, methyl ethyl ketone, ethylene dichloride, toluene, ethyl acetate and mineral spirits. Such resin solutions can be proportionately used in place of the polymer per se provided the volatile solvent introduced thereby is not in excess of 10%, preferably less than 5%, by weight of the final product.

The resulting sealant of this formulation is of handknifing consistency. Although similar in performance to the product of Example 1, this product does not have the toughness of the Example 1 product.

EXAMPLE 6 Percent by wt. Colloidal china clay(oi1 absorption 30) 25.0 Talc (oil absorption 25) 30.0 Zinc oxide 2.0 Chrome yellow pigment 1.0 Xylol 3.0 Polyester plasticizer 5.0 Butyl/isobutyl methacrylate polymer 14.0 VDB-itaconate diester 9.0

VDB-isophthalate diester 9.0 Catalyst, cobaltous butyl phthalate solution 2.0

The methacrylate polymer is a commercially available copolymer prepared by copolymerizing equal weight proportions of n-butyl rnethacrylate and isobutyl methacrylate monomers in accordance with methods well known in the art.

The polyester plasticizer is a 62% oil length castor oil modified glycerol sebacate polyester resin.

The VDB isophthalate diester was prepared in the identical manner as the previously described orthophthalate diester, substituting dimethyl isophthalate for the dimethyl orthophtha-late.

The sealant product of Example 6 was prepared by initially wetting the tiller materials with the polyester plasticizer and the xylol and then adding thereto the methacryl-ate polymer dissolved in the liquid VDB diesters.

This sealant of knife-grade consistency is particularly useful as a calking putty for application to zinc chromate primed aluminum aircraft structures and like fabrication to fill in rivet head cavities and smooth out other surface irregularities. This sealant dried sufiiciently in six hours at room temperature to be sanded. The dried sealant exhibits excellent adhesion to the primer and adequately fills the cavities without detectable shrinkage.

This product was also found to be useful for metal repair on automobile bodies. The repaired surface showed no imperfections when refinished by usual procedures with ordinary automotive refinish enamels.

EXAMPLE 7 Percent by wt.

Magnesium silicate (oil absorption, 20) 45.0 Aluminum Powder 18.0 Methacrylic acid diester of triethylene glycol 12.0 Polymeric fi-cyanoethyl ether of VDB 12.0 Tris-(VDB)-cyanurate 12.0 Cobaltous butyl phthalate solution 1.0 100.0

The tris-(VDB-)-cyanurate was prepared by alcoholysis of 249 parts by weight of triallyl cyanurate and 516 parts of VDB alcohol in the presence of 400 parts of toluol and parts of sodium methoxide. The reaction product mixture was refined to recover the tris-(VDB)-cyanurate.

This product was prepared by initially wetting the filler components with the methacrylic acid diester and the polymeric cya-noether and then mixing the tris-(VDB)-cyanurate and catalyst with the prewet filler.

The performance of this sealant having a metallic appearance is comparable with that of the product of Example 3.

The content of aluminum powder can be increased at the expense of the magnesium silicate if a greater metallic eifect is desired.

Substitution of an equal weight of tris-(VDM)-cyanurate for the tris-(VDB)-cyanurate in the Example 7 formulation provides an equivalent product. The designation VDM is used to identify 2-vinyl-1,3-dioxolane-4-methanol which is obtained as the reaction product of acrolein and glycerol.

Substitution of either polymeric VDB-benzoate or VDM-benzoate, prepared by blowing the respective catalyzed monomeric esters for 60 hours as described for the polymeric fl-cyanoethyl ether, substituted for the polymeric B-cyanoethyl ether of VDB in the Example 7 formulation likewise provides equivalent sealants.

l l t i 1 The indicated sebacic acid diester was prepared by ester interchange between dimethyl sebacate and 2-vinyl- S-methyl-S-methylol-l,3-dioxane, this latter alkanol being the condensation product of acrolein and trimethylolethane.

The perforance of this sealant, characterized by a knife grade consistency of 1080 seconds, as a calking compound is comparable with that of the product of Example 3. The cured product is slightly softer than the product of Example 3 because of the relatively greater length of the dicarboxylic acid radical of the poly-acetal compound.

EXAMPLE 9 Percent by weight Magnesium silicate (oil absorption, 20) a- 54.0

Titanium dioxide (colorant pigment) 9.0

VDB itaconic acid diester 12.0 Polymeric VDB-benzoate 12.0

2(2-vinyl-1',3-dioxolane-4'-butoxy) pyran 12.0

Catalyst, cobaltous butyl phthalate solution 1.0

The polymeric VDB-benzoate was prepared by airblowing the monomeric ester for 60 hours in the presence of cobaltous butyl phthalate in an amount equivalent to .05 of cobalt metal based on the Weight of the VDB- benzoate.

The substituted pyran was prepared by reacting 84 parts of 2,3-dihydropyran with 172 parts by weight of VDB alcohol in the presence of 1 part of oxalic acid and rectifying to recover the substituted pyran.

The performance of this sealant of knife-grade consistency is equivalent to that of the product of Example 3.

Many widely different embodiments of this invention can be made, in light of the teaching herein, in addition to those described in the specific examples and the invention is intended not to be limited except as indicated in the appended claims.

I claim:

1. A sealant composition which is a pressure-deformable cohesive mass consisting essentially of a uniform mixture of (1) an air-curable non-volatile organic binder,

(2) drier selected from the class consisting of soluble salts and soaps of siccative metals in an amount providing 0.0005 %3% of metal based on the weight of said binder and (3) particulate inert filler in the amount of 5%400% based on the weight of said binder;

said sealant composition having a consistency between about 5 seconds and 5000 seconds of time required for 50 revolutions of a two-arm modified Stormer consistency spindle under an applied load of 2000 grams;

said binder consisting essentially of a liquid cyclic acetal compound containing a plurality of cyclic radicals of the following general chemical structure:

represents carbon atoms in the acetal ring, a being an integer having a value of 2 to 3,

all but one of the indicated unsatisfied valences of said carbon atoms of the acetal ring are satisfied by monovalent radicals of the class consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, chloroalkyl, fluoroalkyl, alkoxyalkyl, cyano, chloroalkoxyalkyl, fiuoroalkoxy- 1 alkyl, cyanoalkoxyalkyl, cyanoalkyl, alkenyl, chloroaryl, and fluoroaryl when a is 2, and consisting additionally of fluoro, chloro, acylamido and phenylsulfonyl when a is 3, and the one remaining valence connects the cyclic acetal 1 radical to at least one other such cyclic acetal radical through an interposed polyvalent radical; and R is a monovalent radical of the class consisting of hydrogen, alkyl, alkenyl, aryl, chloro, fluoro, bromo, cyano, acyloxy, chloroalkyl, fluoroalkyl, cyanoalkyl, alkoxy, aryloxy and carbalkoxy,

said interposed polyvalent radical being free of substituents having an inhibiting effect on the air-drying property of said compound.

2. The product of claim 1 wherein said organic binder 2 consists essentially of a mixture of 99%20% by weight of at least one said cyclic acetal compound and 1%80% by weight of at least one non-volatile auxiliary organic binder material soluble therein and innocuous thereto.

3. The product of claim 1 wherein said cyclic acetal compound is an ester of a polycarboxylic acid having the carboxyl substituents thereof satisfied with radicals derived from at least one 2-vinyl-1,3-cyclic acetal alkanol.

4. The product of claim 3 wherein said cyclic acetal compound is the diester of a benzenedicarhoxylic acid.

5. The product of claim 3 wherein said cyclic acetal compound is the diester of an aliphatic dicarboxylic acid.

6. The product of claim 3 wherein said cyclic acetal compound is an ester of an unsaturated polycarboxylic acid having at least one polymerizable C=CH vinylidene moiety.

7. The product of claim 6 wherein said unsaturated polycarboXylic acid is itaconic acid.

8. The product of claim 1 wherein said filler consists essentially of finely-divided particulate silica.

References Cited in the file of this patent UNITED STATES PATENTS 2,401,776 Rothrock June 11, 1946 2,902,476 Kern Sept. 1, 1959 FOREIGN PATENTS 757,573 Great Britain Sept. 19, 1956 1,111,187 France Oct. 26, 1955 OTHER REFERENCES Bostwich et 211.: Filed Polyethylene Compounds, Ind. & Eng. Chem., volume 42, pages 848-849, May 1950. 

1. A SEALANT COMPOSITION WHICH IS A PRESSURE-DEFORMABLE COHESIVE MASS CONSITING ESSENTIALLY OF A UNIFORM MIXTURE OF (1) AN AIR-CURABLE NON-VOLATILE ORGANIC BINDER, (2) DRIER SELECTED FROM THE CLASS CONSISTING OF SOLUBLE SALTS AND SOAPS OF SICCATIVE METALS IN AN AMOUNT PROVIDING 0.0005%-3% OF METALS IN AN AMOUNT OF SAID BINDER AND (3) PARTICULAR INERT FILLER IN THE AMOUNT OF 5%-400% BASED ON THE WEIGHT OF SAID BINDER SAID SEALANT COMPOSITION HAVING A CONSISTENCY BETWEEN ABOUT 5 SECONDS AND 5000 SECONDS OF TIME REQUIRED FOR 50 REVOLUTIONS OF A TWO-ARM MODIFIED STROMER CONSISTENCY SPINDLE UNDER AN APPLIED LOAD OF 200 GRAMS; SAID BINDER CONSISTING ESSENTIALLY OF A LIQUID CYCLIC ACETAL COMPOUND CONTAINING A PLURALITY OF CYCLIC RADICALS OF THE FOLLOWING GENERAL CHEMICAL STRUCTURE: 